1. Field
Embodiments relate to a chemical mechanical polishing (CMP) apparatus for planarizing a surface of a wafer or a layer formed on the wafer.
2. Description of the Related Art
As semiconductor devices become highly integrated and obtain larger capacities, step differences of material layers formed on the semiconductor devices, for example, metal interconnections, also increase. The step differences of the metal interconnections may make it difficult to pattern the metal interconnections. In particular, since step differences of a cell region and a peripheral region in a memory device are increased, the higher the metal interconnections become, the more serious problems related to the step differences become. Therefore, in manufacturing semiconductor devices, a planarization technique for planarizing a material layer or a semiconductor substrate itself is essentially required.
A chemical mechanical polishing (CMP) process, a typical planarization technique among semiconductor manufacturing processes, is a process of planarizing a surface of a wafer or a material layer formed on the wafer by combining a mechanical polishing effect by a polishing agent with a chemical reaction effect by an acid or base solution.